Research on grid synchronization of grid-side converter in direct drive wind power generation system

In grid-side converter control in direct drive wind power generation system, grid voltage oriented vector control strategy is used. The fast and precise detection of the amplitude and phase of the fundamental frequency voltage components is a crucial issue in the design of grid synchronization of grid-side converter. Because the dynamic performance of the phase-locked loop based on the single synchronous reference frame PLL is dissatisfactory when the grid voltage is unbalanced and distorted, the paper proposes an enhanced PLL system combining positive sequence computation unit and phase-locked method. Using this method can realize fast and precise detection of the amplitude and phase of the fundamental frequency voltage positive sequence component in the presence of voltage unbalance and distortion. Simulation results verify the effectiveness of the proposed scheme.